Pump, cooler, and electronic device

ABSTRACT

According to one embodiment, a pump housing comprises a heat receiving plate which is thermally coupled to a CPU, and a pump chamber. An impeller to be rotated by a motor is provided in the pump chamber. At least a part of the pump housing is made of resin containing at least one of metal filler, filler of material having lower linear expansion coefficient than the resin, and filler of material having lower water-vapor transmissivity than the resin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-133536, filed Apr. 28, 2004, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. FIELD

Embodiments of the invention relate to a pump implemented in a cooler of a liquid cooling type that cools heat-generating elements such as a central processing unit (CPU) by using a liquid coolant. The invention further relates to a cooler having the pump and to an electronic device having the cooler.

2. DESCRIPTION OF THE RELATED ART

With enhancement in processing speed and multi-functionality, CPUs for use in electronic devices are generating an increased amount of heat during operation. In recent years, by way of a countermeasure for such heat generation, electronic devices have been put into practice that cool a CPU by using a liquid coolant having a specific heat coefficient significantly higher than air. The cooling of the electronic devices is conducted by a cooler of a so-called liquid cooling type.

Herein, as a cooler of the type being equipped in an electronic device, coolers with a contact-heat-exchange pump have been proposed. The contact-heat-exchange pump is brought into close contact with a heat-generating electronic component like a CPU, whereby heat exchange is performed between the heat-generating electronic component and the liquid coolant thereby to cool the heat-generating electronic component, and the liquid coolant is circulated.

The contact-heat-exchange pump has a casing cover, a pump casing having a heat receiving surface that is heat-connected to the heat-generating electronic component and a pump chamber. The casing cover hermetically encloses the pump chamber. The pump casing and the casing cover are made of a high thermal conductivity material, such as copper or aluminum to accelerate heat transfer. One such contact-heat-exchange pump is disclosed in Japanese Patent No. 3452059.

In the case where a pump casing, a casing cover, and the like components are manufactured by die casting of, for example, copper or aluminum. The die cast manufacturing costs tend to be higher than manufacturing using resin injection molding. In addition, a pump of this type is generally configured such that a rotor is provided inside of a pump chamber, and a stator is provided in an outer side of the pump chamber through a casing cover. A motor having the rotor and the stator rotates an impeller provided in the pump chamber. For this configuration, in order to rotate the impeller optimally, that is, to drive the motor optimally, the casing cover between the rotor and the stator is preferably a dielectric material. For this reason, demand occurs for forming of such a pump casing and a casing cover from resin material.

In the configuration where the pump casing, the casing cover, and the like components are made of resin, however, with the loss of coolant is more likely to occur than the configuration where the pump casing, the casing cover, and the like components made of copper or aluminum. More specifically, liquid coolant in the pump chamber is more likely to, for example, evaporate or leak from the components themselves or through sealed portions between the pump casing and the casing cover.

BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.

FIG. 1 is a perspective view showing a portable computer according to an embodiment of the present invention;

FIG. 2 is a perspective view of the portable computer shown in FIG. 1, as viewed from the side of exhaust openings of a first housing;

FIG. 3 is a plan view of an exemplary embodiment of a cooler housed in the first housing;

FIG. 4 is an exploded perspective view of an exemplary embodiment of a pump;

FIG. 5 is a perspective view of the pump of FIG. 4 in a state where a second cover is removed; and

FIG. 6 is a cross-sectional view showing the positional relationship between a CPU and a pump that are mounted on a printed circuit board.

DETAILED DESCRIPTION

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

FIGS. 1 and 2 show a portable computer 1 as being an electronic device. The portable computer 1 has a computer main body 2 and a display unit 3. The computer main body 2 has a first housing 10. The first housing 10 has a bottom wall 11 a, an upper wall 11 b, a front wall 11 c, left and right sidewalls 11 d and 11 e, a rear wall 11 f.

Referring to FIG. 1, the upper wall 11 b has a palm rest 12 and a keyboard mounting portion 13. The keyboard mounting portion 13 is provided in a rear portion of the palm rest 12. A keyboard 14 is mounted in the keyboard mounting portion 13. The front wall 11 c, the left and right sidewalls 11 d and 11 e, and the rear wall 11 f form a peripheral wall along the periphery of the first housing 10. With reference to FIG. 2, a plurality of exhaust openings 15 are formed in a peripheral wall of the first housing 10, such as the rear wall 11 f. The exhaust openings 15 are aligned in the width direction of the first housing 10.

Referring again to FIG. 1, the display unit 3 has a second housing 20 and a liquid crystal display panel 21 as being a display panel. The LCD panel 21 is accommodated in the second housing 20. The LCD panel 21 has a screen 21 a that displays images. The screen 21 a of the liquid crystal display panel 21 is exposed outwardly of the second housing 20 through an opening portion 22 formed on a front plane of the second housing 20.

The second housing 20 is supported through a hinge (not shown) to a rear end portion of the first housing 10. As such, the display unit 3 is rotatable between a closing position and an open position. The closing position is a position where the display unit 3 is folded so as to cover the palm rest 12 and the keyboard 14 (see FIG. 2). The open position is a position where the display unit 3 is rotated upward, causing the palm rest 12, the keyboard 14, and the screen 21 a to be exposed (see FIG. 1).

Referring now to FIG. 3, a printed circuit board 30 is accommodated in the first housing 10. More specifically, as is shown in FIG. 6, the printed circuit board 30 is disposed in parallel with the bottom wall 11 a of the first housing 10. A CPU 31, as being a heat-generating unit, is mounted on an upper face of the printed circuit board 30. According to one embodiment of the invention, the CPU 31 constitutes a microprocessor, which serves as a central functionality of the portable computer 1. According to other embodiments of the invention, the CPU 31 may constitute a digital signal processor, an application specific integrated circuit, a controller or the like. The CPU 31 has a base substrate 32 and an integrated circuit (IC) chip 33 generally disposed in a central portion of the upper face of the base substrate 32. With enhancement in properties such as processing speed and multi-functionality, the IC chip 33 generates a very large amount of heat during operation, therefore requiring to be cooled in order to maintain stabilized operation.

Referring back to FIG. 3, the portable computer 1 has a liquid-cooling type cooler 40 for cooling the CPU 31 by using a liquid coolant such as antifreeze. The cooler 40 is accommodated in the first housing 10. The cooler 40 has components such as a pump 100 concurrently serving as a heat receiving portion and a heat exchanger; a heat radiation portion 50; a circulation path 60; and an electric fan 70.

As shown in FIGS. 3 to 6, the pump 100 causes a liquid coolant to forcedly circulate and flow in the circulation path 60. The pump 100 has a pump housing 101 concurrently serving as being a heat receiving portion; an impeller 102; a motor 103 having a rotor 103 a and a stator 103 b; and a control board 104.

The pump housing 101 has a configuration having a housing body 110, a first cover 111, and a second cover 112. The housing body 110 has a shape like a flat book that is larger than the CPU 31 and that has a recess portion 113 upwardly opened.

The housing body 110 has a configuration having a frame-like main-body primary portion 121 constituting a sidewall (side face) of the housing body 110; and a heat receiving plate 122 serves as being a heat receiving portion with which the end of an opening opened downwardly of the main-body primary portion 121 is liquid-tight blocks. That is, the main-body primary portion 121 defines the side face of the recess portion 113, and the heat receiving plate 122 defines the bottom face of the recess portion 113. In other words, the recess portion 113 is defined by the inner face of the main-body primary portion 121 and the upper face of the heat receiving plate 122. The heat receiving plate 122 concurrently serving as the bottom wall of the recess portion 113 opposite the CPU 31. The lower face of the heat receiving plate 122 is formed to be a substantially flat heat receiving face 122 a. An o-ring 124 is interposed between the main-body primary portion 121 and the heat receiving plate 122. The housing body 110 may be a unitary structure.

The first cover 111 blocks the opening end of the recess portion 113. An o-ring 123 is provided between the housing body 110 and the first cover 111. The upper face of the first cover 111 has a stator-accommodating recess portion 115 for accommodating the stator 103 b and a control-board accommodation recess portion 116 for accommodating the control board 104.

An interior portion of the pump housing 101, that is, an area surrounded by the recess portion 113 and the first cover 111 is partitioned by a ring-like partition wall 117 into a pump chamber 118 and a reservoir tank 119. The partition wall 117 is integrated with the housing body 110 (with the main-body primary portion 121, in the present embodiment) into a unitary body. The pump chamber 118 is provided close to the side of one of four corner portions of the pump housing 101. More specifically, a center position of the pump chamber 118 is off-centered with respect to a center position of the pump housing 101. The reservoir tank 119 for storing the liquid coolant is provided so as to surround the pump chamber 118 from the remaining three of the four corner portions of the pump housing 101.

In addition, an inlet conduit 131 and an outlet conduit 132 are provided in the housing body 110 (the main-body primary portion 121, in the present embodiment). The inlet conduit 131 and the outlet conduit 132 are disposed horizontally spaced apart from each other. An upstream end of the inlet conduit 131 outwardly protrudes through the sidewall of the housing body 110 (the main-body primary portion 121, in the present embodiment). A downstream end of the inlet conduit 131 is opened to the inside of the reservoir tank 119 and is opposite a communication opening 130 formed within the partition wall 117. Although not shown, gas-liquid separation spacing is provided between the downstream end of the inlet conduit 131 and the communication opening 130. The spacing is all time positioned under the liquid level of the liquid coolant stored in the reservoir tank 119 even if the pump housing 101 changes its orientation.

A downstream end of the outlet conduit 132 outwardly protrudes through the sidewall of the housing body 110 (the main-body primary portion 121, in the present embodiment), and is located in juxtaposition with the upstream end of the inlet conduit 131. An upstream end of the outlet conduit 132 extends through the partition wall 117, and is opened to the inside of the pump chamber 118.

The disc-shaped impeller 102 transfers the liquid coolant from the interior side of the pump housing 101 to the outer side thereof (circulation path 60), and is accommodated in the pump chamber 118. The impeller 102 is made of a resin material (hereinafter referred to as “resin”), and has a rotation axis 102 a in a rotation center portion thereof. The rotation axis 102 a is disposed between the first cover 111 and the heat receiving plate 122 to extend there across, whereby the rotation axis 102 a is rotatably supported by the first cover 111 and the heat receiving plate 122.

The motor 103 rotatably drives the impeller 102. The rotor 103 a, which constitutes a component of the motor 103, has a magnet magnetized through multiple anodes and multiple cathodes and has a ring-like shape. The rotor 103 a is accommodated in the pump chamber 118 and secured to an upper face of the impeller 102 in axial alignment with the impeller 102.

The stator 103 b, which constitutes a component of the motor 103, is accommodated in the stator-accommodatimg recess portion 115 formed on the upper face of the first cover 111. The stator 103 b should be provided in correlation to the rotor 103 a through the first cover 111. As such, the stator-accommodating recess portion 115 is provided in a position correlating to the rotor 103 a. More specifically, a center position of the stator-accommodating recess portion 115 is off-centered with respect to a center position of the first cover 111. The control-board accommodation recess portion 116 is provided in a position set not to come in the position of the stator-accomodating recess portion 115.

An opening end of the recess portion 113 is blocked by the first cover 111 to allow the stator-accommodating recess portion 115 to enter the inside of the rotor 103 a. More specifically, the stator 103 b is coaxially accommodated inside of the rotor 103 a through the first cover 111. The stator 103 b is electrically connected to the control board 104.

Conduction to the stator 103 b is performed at the same time as a power-on operation of the portable computer 1. By the conduction, a rotation magnetic field occurs in the circumferential direction of the stator 103 b, and the magnetic field and the rotor 103 are magnetically coupled. As a consequence, a rotating torque along the circumferential direction of the impeller 102 is generated between the stator 103 b and rotor 103 a, whereby the impeller 102 is rotated.

The second cover 112 is secured to an upper face of the first cover 111. The stator 103 b and the control board 104 are shrouded by the second cover 112. The second cover 112 is provided to restrain leak, evaporation, or the like of the liquid coolant, and may be omitted.

Materials for forming the pump housing 101 will be described hereafter. As described above, the first cover 111 is provided between the rotor 103 a and the stator 103 b. If the first cover 111 is made of a conductive material, there may occur a risk of influencing the operation of the rotor 103 a. If the first cover 111 is made of a metal material, the pump 100 is likely to be heavy. As such, at least the first cover 111 of the pump housing 101 is preferably made of resin according to one embodiment of the invention.

The main-body primary portion 121 has a relatively complex structure. Therefore, if the main-body primary portion 121 is made of a metal material, the cost of a die-cast mold and its manufacturing are likely to be substantial. If the main-body primary portion 121 is made of a metal material, the pump 100 is likely to be heavy. As such, the main-body primary portion 121 as well is according to one embodiment of the invention made of resin.

In the present embodiment, at least a part (i.e., component) of the pump housing 101 including, for example, the main-body primary portion 121 and the first cover 111, are made of resin containing at least one of metal filler, filler of material having a lower linear expansion coefficient than the resin, and filler of material having a lower water-vapor transmissivity than the resin. This makes it possible to obtain the pump 100 that is easy in manufacture, low in cost, light in weight and that can restrain liquid-coolant reduction due to evaporation, leakage, or the like. Accordingly, the pump 100 capable of optimally cooling for a long time can be obtained.

More specifically, many metals are not only superior in thermal conductivity, but also lower than resin in linear expansion coefficient and water-vapor transmissivity. For this reason, the main-body primary portion 121 and the first cover 111 are made of the resin containing this type of metal filler. This enables obtaining the main-body primary portion 121 and the first cover 111 that are lower in linear expansion coefficient than in the case where they are made of resin only. Thereby, reduction can be implemented for the difference in the linear expansion coefficients of the first cover 111 and the main-body primary portion 121 and the difference in the linear expansion coefficients of the main-body primary portion 121 and the heat receiving plate 122. Consequently, the liquid coolant can be restrained from leaking through the gap formed between the first cover 111 and the main-body primary portion 121 and the gap between the main-body primary portion 121 and the heat receiving plate 122, both gaps formed due to the difference in liner expansion coefficient.

Moreover, since the main-body primary portion 121 and the first cover 111 are made of the resin containing the metal filler, the main-body primary portion 121 and the first cover 111 are lower in water-vapor transmissivity than if they were only made of resin. Thereby, the liquid coolant can be restrained from evaporating from the pump housing 101.

In addition, since the main-body primary portion 121 and the first cover 111 are made of the resin containing the metal filler, the main-body primary portion 121 and the first cover 111 exhibit higher heat transfer effect in comparison to a configuration where main-body primary portion 121 and the first cover 111 are made only of resin. Thereby, heat generated in the CPU 31 can quickly be transferred the liquid coolant.

Further, since the main-body primary portion 121 and the first cover 111 are made of the resin containing the metal filler, the weight of the pump housing 101 can be reduced in comparison to the case where they are made of a metal material.

For the metal filler, filler such as a copper filler, an aluminum filler, or an aluminum alloy filler can be suitably used.

When the main-body primary portion 121 and the first cover 111 are made of the resin containing the filler material having a lower linear expansion coefficient than resin, the main-body primary portion 121 and the first cover 111 would possess a lower linear expansion coefficient than the resin. This can reduce the differences in linear expansion coefficient between the first cover 111 and the main-body primary portion 121 and between the main-body primary portion 121 and the heat receiving plate 122. Consequently, the liquid coolant can be restrained from leaking from gaps formed between the first cover 111 and the main-body primary portion 121 and between the main-body primary portion 121 and the heat receiving plate 122.

Further, when the main-body primary portion 121 and the first cover 111 are made of the resin containing the filler material having lower water-vapor transmissivity than resin, the main-body primary portion 121 and the first cover 111 would possess a lower water-vapor transmissivity than if these elements 121 and 111 were made of only resin. Thereby, the liquid coolant can be restrained from evaporating from the pump housing 101. Consequently, heat generated in the CPU 31 can be quickly transferred to the liquid coolant through, for example, the heat receiving plate 122.

Further, when the main-body primary portion 121 and the first cover 111 are made of resin containing filler material having a lower linear expansion coefficient than resin, or with filler material having a lower water-vapor transmissivity than resin, the weight of the pump housing 101 can be reduced in comparison to the case where the main-body primary portion 121 and the first cover 111 are made of a metal material.

Not only metals, but most carbon and ceramic materials, linear expansion coefficients and water-vapor transmissivities thereof are low. Thus, any filler made of material having a lower linear expansion coefficient than resin or material having a lower water-vapor transmissivity than resin, such as a metal filler, a carbon filler, a semiconductor filler or a ceramic filler for example, can be suitably used. Examples of ceramic fillers include, but are not limited or restricted to, alumina (aluminum oxide) filler or aluminum nitride.

For the resin containing the filler, for example, a polycarbonate or ABS resin can be used. With such the resin being used, the strength required for the pump housing 101 can be maintained.

The following shows representative linear expansion coefficients of respective materials: Semiconductor silicon: 3 ppm/° C. Ceramic (alumina): 7 ppm/° C. Carbon: 2 to 7 ppm/° C. Copper: 17 ppm/° C. Aluminum: 22 ppm/° C. Polycarbonate: 70 ppm/° C. ABS resin: 74 ppm/° C.

On the other hand, to optimally cool the CPU 31 the heat receiving plate 122 is preferably made of a metal material having a high thermal conductivity. For one embodiment, the heat receiving plate 122 is made of, for example, copper that has a high thermal conductivity. As in the present embodiment, when the housing body 110 is formed by being separated into the main-body primary portion 121 and the heat receiving plate 122, the heat receiving plate 122 can become selectively be made of a high-conductivity material.

Further, the second cover 112 is preferably made of a metal material to enhance the effects of restraining liquid coolant leakage and evaporation occurring in association with the second cover 112. According to one embodiment, the second cover 112 is made of, for example, an aluminum or aluminum alloy material.

The pump 100 is disposed on the printed circuit board 30 in such a manner as to cover the CPU 31 from the upper portion thereof. With reference to FIG. 6, the pump housing 101 of the pump 100 is secured together with the printed circuit board 30 to the bottom wall 11 a of the first housing 10. The bottom wall 11a has boss portions 17 in positions corresponding to four corner portions of the pump housing 101. The boss portions 17 upwardly project from the bottom wall 11 a. The printed circuit board 30 is overlaid on tip faces of these boss portions 17. In FIG. 6, numeral 34 denotes a reinforcing plate for reinforcing the printed circuit board 30 from the lower face thereof.

Employing a below-described mounting mechanism, the pump 100 is mounted to the bottom wall 11 a of the first housing 10 such as to cover the CPU 31 from the upper portion thereof. Recess portions 141 are provided in the respective four corner portions of the pump housing 101. A bottom wall (corner portions of the heat receiving plate 122) defining the recess portions 141 has through-holes 142 that allow cylindrical inserts 143 to pass through. The cylindrical inserts 143 each have a projection portion 143 a projecting to the outer side in the horizontal direction along the circumferential direction on the upper edge. Additionally, the cylindrical insert 143 has a groove portion 143 b formed along the circumferential direction.

The pump 100 is compressed by the mounting mechanism against the CPU 31 in the following manner. Firstly, the cylindrical insert 143 is passed in through a coiled spring 144. The cylindrical insert 143 is inserted from an upwardly opened opening end of the recess portions 141 of the first cover 111, and the groove portion 143 b is positioned lower than the heat receiving face 122 a of the pump 100. A fall-out prevention c-ring 145 is fitted to the groove portion 143 b. Thereby, the cylindrical insert 143 is mounted to the pump 100 in the state that the projection portion 143 a is urged by the coiled spring 144 to be apart from the bottom wall defining the recess portions 141.

A conductive grease (not shown) is applied on an upper face of the IC chip 33, and the heat receiving face 122 a of the pump housing 101 is placed to oppose the IC chip 33. A screw 146 passed in through the cylindrical insert 143 is screwed into the boss portion 17 formed on the printed circuit board 30. Thereby, the cylindrical insert 143 is secured to the boss portion 17, and the pump 100 is urged by resilience of the coiled spring 144 against the IC chip 33. Thereby, the IC chip 33 is thermally coupled to the heat receiving face 122 a of the pump housing 101 through the conductive grease.

In the portable computer 1, the pump 100 is secured on the printed circuit board 30 such that the center of the pump housing 101 (center of the heat receiving face 122 a) matches the center of the IC chip 33. However, the center (rotation axis 102 a) of the impeller 102 is deviated from the center of the pump housing 101. As such, the center of the IC chip 33 is deviated from the center of the impeller 102 opposing it, with the pump housing 101 interposed therebetween. This arrangement enables the liquid coolant to absorb a maximum possible amount of heat of the IC chip 33. That is, according to one embodiment of the invention, the IC chip 33 is opposed to a position where the liquid coolant flows fast with the pump housing 101 interposed therebetween in order to cause the liquid coolant to absorb a maximum possible amount of the liquid coolant. As is already known, the flow of the liquid coolant generated by the rotation of the rotor 103 a becomes faster as leaving further from the center of the impeller 102. Therefore, with the above configuration, a larger amount of the heat of the IC chip 33 is absorbed in the liquid coolant.

As is shown in FIG. 3, the heat radiation portion 50 has a heat-radiation-portion main body 51 and multiple heat radiation fins 57 thermally coupled with a heat-radiation-portion main body 51. The heat-radiation-portion main body 51 is configured of piping through which the liquid coolant flows. The heat-radiation-portion main body 51 has a coolant inlet opening 54 and a coolant outlet opening (provided on a depth side of the coolant inlet opening as viewed across the paper face of FIG. 3, although it is not visibly shown), whereby to allow the coolant to flow inside.

According to one embodiment of the invention, the heat-radiation-portion main body 51 is made of substantially U-shaped piping. One opening end of the piping serves as the coolant inlet opening 54, and the other opening end of the piping serves as the coolant outlet opening. Thus, the piping of the heat radiation portion 50 (heat-radiation-portion main body 51) constitutes a portion of the circulation path 60 (which will be described below in more detail).

The heat radiation fins 57 are made of a metal material, such as an aluminum alloy or copper material, which is excellent in thermal conductivity. The heat radiation fins 57 are formed as a rectangular plate. The heat radiation fins 57 are arranged in parallel to and spaced from one another. The heat radiation fins 57 are soldered to the heat-radiation-portion main body 51.

The heat radiation portion 50 is accommodated in the first housing 10, wherein the heat radiation fins 57 are positioned opposite the exhaust openings 15 of the first housing 10. According to one embodiment of the invention, a pair of brackets 58 is soldered to the heat radiation portion 50. The brackets 58 are each secured with a screw to a boss portion (not shown) projecting from the bottom wall 11 a of the first housing 10. In this manner, the heat radiation portion 50 is secured to the bottom wall 11 a of the first housing 10.

The circulation path 60 has first piping 61, second piping 62, and piping (heat-radiation-portion main body 51) that belongs to the heat radiation portion 50. That is, the heat-radiation-portion main body 51 serves concurrently as the heat radiation portion 50 and the circulation path 60. The first piping 61 connects the outlet conduit 132 of the pump 100 to the coolant inlet opening 54 of the heat radiation portion 50. The second piping 62 connects the inlet conduit 131 of the pump 100 and the coolant outlet opening of the heat radiation portion 50. Thereby, the liquid coolant passes through the first and second piping 61 and 62 and circulates between the pump 100 and th eheat radiation portion 50.

The electric fan 70 blows cooling air to the heat radiation portion 50, and is disposed immediately before the heat radiation portion 50. The electric fan 70 has a fan casing 71 and a centrifugal impeller 72 accommodated in the fan casing 71. The fan casing 71 has an outlet opening 71 a for drawing out cooling air. The outlet opening 71 a is connected to the heat radiation portion 50 through a duct 73.

The impeller 72 is driven by a motor (not shown), for example, at power-on of the portable computer 1 and when the temperature of the CPU 31 has reached a predetermined level. Thereby, cooling air is supplied from the outlet opening 71 a of the fan casing 71 to the heat radiation portion 50.

Operation of the cooler 40 will be described below.

The IC chip 33 of the CPU 31 generates heat during use of the portable computer 1. The heat generated by the IC chip 33 transfers to the pump housing 101 through the heat receiving face 122 a of the pump 100. The recess portion 113 (the pump chamber 118 and the reservoir tank 119) of the pump housing 101 is filled with the liquid coolant, so that the liquid coolant absorbs much of the heat transferred to the pump housing 101.

An electric current is supplied to the stator 103 b of the motor 103 when the portable computer 1 is switched on. Thereby, a rotating torque occurs between the stator 103 b and the rotor 103 a, whereby the rotor 103 a is rotated with the impeller 102. Upon rotation of the impeller 102, the liquid coolant in the pump chamber 118 is compressed and drawn out from the outlet conduit 132, and concurrently, is led into the heat radiation portion 50 from the coolant inlet opening 54 through the first piping 61. The liquid coolant heated by heat exchange in the pump housing 101 flows from the coolant inlet opening 54 side to the side of the coolant outlet opening, during which the heat of the IC chip 33 absorbed by the liquid coolant transfers to the heat radiation fins 57.

Upon rotation of the impeller 72 of the electric fan 70 during use of the portable computer 1, cooling air flows to the heat radiation portion 50 from the outlet opening 71 a of the fan casing 71. The cooling air passes through between the heat radiation fins 57 being adjacent to one another. Thereby, components such as the heat radiation fins 57 and the heat-radiation-portion main body 51 are cooled. Then, most of the heat transferred to the heat radiation fins 57 and the heat-radiation-portion main body 51 is discharged to the outer side of the first housing 10 from the exhaust opening 15 as cooling air thus flows.

The liquid coolant cooled in the heat radiation portion 50 is guided into the inlet conduit 131 of the pump housing 101 through the second piping 62. The liquid coolant is returned from the inlet conduit 131 to the reservoir tank 119. The liquid coolant thus returned to the reservoir tank 119 again absorbs heat of the IC chip 33 while being sucked in the pump chamber 118.

In iteration of the operation cycle, heat of the IC chip 33 is progressively transferred to the heat radiation portion 50, is carried on the cooling air flow passing through the heat radiation portion 50, and is thereby discharged to the outer side of the first housing 10.

As described above, in the pump 100, cooler 40, and portable computer 1 having the pump 100 according to the present embodiment, at least the one part (component) of the pump housing 101 is made of the resin containing one of (1) a metal filler, (2) a filler of the material having lower linear expansion coefficient than the resin, and (3) a filler of the material having lower water-vapor transmissivity than the resin. Accordingly, coolant evaporation, or leak is restrained, thereby the CPU 31 is optimally cooled for a long time.

In the pump 100 of the present embodiment, while the main-body primary portion 121 and the first cover 111 are made of the resin containing at least one of metal filler, carbon filler, and ceramic filler, the main-body primary portion 121 and the first cover 111 is not limited to the above-described filler materials and other parts of the pump housing 101 may be formed with side filler material. For instance, the heat receiving plate 122 and the second cover 112 may be made of the resin containing the above-described filler. The main-body primary portion 121 may be made of material, such as a metal material, having high thermal conductivity to enhance heat-exchange effects in the pump housing 101.

The housing body 110 may be such that a part (component) other than the heat receiving face 122 a is made of the resin. In this case, parts of the housing body 110 other than the heat receiving portion including the heat receiving face 122 a may be made of a resin containing a filler material having lower linear expansion coefficient than the resin and/or filler material having lower water-vapor transmissivity than the resin.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

1. A pump comprising: an impeller; and a pump housing coupled to the impeller, the pump housing comprises a plurality of components including a housing body coupled to a first cover, at least one component of the plurality of components being made of a resin containing at least one of (i) a metal filler, (ii) a filler of material having lower linear expansion coefficient than the resin, and (iii) a filler of material having a lower water-vapor transmissivity than the resin.
 2. A pump according to claim 1, wherein the first cover of the pump housing being made of the resin.
 3. A pump according to claim 2, wherein the plurality of components of the pump housing further comprise a main-body primary portion and a heat receiving plate thermally coupled to the main-body primary portion, the main-body primary portion also being made of the resin.
 4. A pump according to claim 1, wherein the plurality of components of the pump housing further comprise a main-body primary portion and a heat receiving plate thermally coupled to the main-body primary portion, the main-body primary portion being made of the resin.
 5. A pump according to claim 1, wherein the plurality of components of the pump housing comprise a main-body primary portion and a heat receiving plate thermally coupled to the main-body primary portion, the heat receiving plate being made of the resin.
 6. A pump according to claim 1, wherein the impeller is situated within a recessed portion formed within an interior of the pump housing with the first cover of the pump housing covering an opening of the recessed portion.
 7. A pump according to claim 1 further comprising a motor adapted to rotate the impeller.
 8. A pump according to claim 7, wherein the motor comprises a rotor positioned within the housing body and a stator positioned coaxially inside the rotor to produce a magnetic field causing rotation of the impeller.
 9. A pump according to claim 1, wherein the at least one component of the plurality of components is made of the resin including of a non-metal filler having a lower linear expansion coefficient than the resin.
 10. A pump according to claim 1, wherein the at least one component of the plurality of components is made of the resin including of a non-metal filler having a lower water-vapor transmissivity than the resin.
 11. A pump according to claim 1, wherein the at least one component of the plurality of components is made of the resin containing the metal filler having a lower water-vapor transmissivity than the resin.
 12. A cooler comprising: a heat radiation portion; a pump to forcibly circulate coolant to the heat radiation portion, the pump including a pump housing and an impeller rotationally coupled to the pump housing, the pump housing comprises a plurality of components including (a) a first cover, (b) a main-body primary portion coupled to the first cover and including an input conduit and an outlet conduit, and (c) a heat receiving plate thermally coupled to the main-body primary portion, where at least two of the first cover, the main-body primary portion and the heat receiving plate being made of a resin containing at least one of (i) a metal filler, (ii) a filler of material having lower linear expansion coefficient than the resin, and (iii) a filler of material having a lower water-vapor transmissivity than the resin; a first piping coupled to the outlet conduit of the pump and the heat radiation portion, the first piping to route the coolant heated at the pump to the heat radiation portion; and a second piping coupled to the inlet conduit of the pump and the heat radiation portion, the second piping to route the coolant cooled by the heat radiation portion to the pump.
 13. A cooler according to claim 12, wherein the heat radiation portion comprising: a third piping including a first opening coupled to the first piping and a second opening coupled to the second piping; and a plurality of heat radiation fins thermally coupled with the third piping.
 14. A cooler according to claim 12, wherein the first cover and the main-body primary portion of the pump housing are made of the resin.
 15. A cooler according to claim 12, wherein the pump further comprises a motor adapted to rotate the impeller.
 16. A pump according to claim 12, wherein the at least two of the first cover, the main-body primary portion and the heat receiving plate are made of the resin containing the metal filler and the metal filler having a lower linear expansion coefficient than the resin.
 17. A pump according to claim 12, wherein the at least two of the first cover, the main-body primary portion and the heat receiving plate are made of the resin containing the metal filler and the metal filler having a lower water-vapor transmissivity than the resin.
 18. An electronic device comprising: a heat generating unit implemented within a first housing; and a cooler comprises a pump including a pump housing and an impeller rotationally coupled to the pump housing for circulating coolant, the pump housing including a cover being made of a resin containing at least one of (i) a metal filler, (ii) a filler of material having lower linear expansion coefficient than the resin, and (iii) a filler of material having a lower water-vapor transmissivity than the resin, including an input conduit and an outlet conduit, and a main-body primary portion coupled to the cover being made of the resin.
 19. An electronic device according to claim 18, wherein the cooler further comprises: a heat radiation portion including a piping including a first opening and a second opening, and a plurality of heat radiation fins thermally coupled to the piping; a first piping coupled between (i) an outlet conduit placed within the main-body primary portion of the pump and (ii) the first opening of the piping of the heat radiation portion, the first piping to route the coolant heated at the pump to the piping; and a second piping coupled to (i) an inlet conduit placed within the main-body primary portion of the pump and (ii) the second opening of the piping of the heat radiation portion, the second piping to route the coolant cooled by the plurality of heat radiation fins to the pump.
 20. An electronic device according to claim 18, wherein the pump of the cooler further comprises a motor adapted to rotate the impeller. 